The major component of these studies deals with a particular female behavior, the lordosis reflex, in female guinea pigs. This behavior is regulated in a predictable and precise manner by two categories of steroids, estrogens and progestins. The object of the research is to use this predictable relationship between a behavior and hormones to analyze the mechanism of action of hormones in the central nervous system. The analysis uses techniques such as intracerebral implantation of hormones (to localize sites of hormone action), administration of anti-hormones, administration of radioactive hormones (to study localization and metabolism of hormones), and assessment of macromolecular receptors for steroid hormones in cytosol and nuclear fractions of brain tissue. The effects of steroid hormones on behavior must be mediated by neurotransmitters. To continue the analysis we evaluate the influence of monoaminergic transmitters on the expression of steroid-induced lordosis behavior. To proceed with this evaluation we use a variety of agents that stimulate or block transmitter receptors, or that inhibit transmitter synthesis. We also measure monoamine levels in localized brain areas after such manipulations. The emerging picture from our work and the work of others, is one of predictable and quantifiable interrelationships among environmental factors, hormones, neurotransmitters and behavior. But the picture is far from complete. Without further work to establish these types of relationships more firmly in non-human species there can be no basic understanding of the way in which chemical and environmental factors influence the brain and alter behavior in all species, including the human.